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United States Patent |
6,206,643
|
Jeong
|
March 27, 2001
|
Method for controlling reciprocating compressor having variable capacity
Abstract
A method of controlling a reciprocating compressor comprising of starting
the reciprocating compressor at a minimum speed in which a frequency of
45-52 Hz is applied, operating the reciprocating compressor at a frequency
of 52.about.60 Hz and operating the reciprocating compressor at a
predetermined rotational speed. Therefore, an optimum amount of
lubricating oil is supplied to a sliding part of the reciprocating
compressor so that the reliability of parts thereof is secured.
Inventors:
|
Jeong; Won-Bae (Seoul, KR)
|
Assignee:
|
Samsung Electronics Co., Ltd. (Suwon, KR)
|
Appl. No.:
|
333934 |
Filed:
|
June 16, 1999 |
Foreign Application Priority Data
Current U.S. Class: |
417/45; 318/778; 318/808; 417/42 |
Intern'l Class: |
F04B 49//06; 7/; H02P 1/2/6; 5/28/ |
Field of Search: |
417/42,45,44.1
318/778,807
|
References Cited
U.S. Patent Documents
Re33620 | Jun., 1991 | Persem | 62/215.
|
2629075 | Feb., 1953 | Deschmann | 318/147.
|
4100466 | Jul., 1978 | Schroeder | 318/102.
|
4401933 | Aug., 1983 | Davy et al. | 318/778.
|
4422030 | Dec., 1983 | McAllise | 318/779.
|
4481455 | Nov., 1984 | Sugimoto | 318/778.
|
4566289 | Jan., 1986 | Iizuka et al. | 62/228.
|
4633382 | Dec., 1986 | Upadhyay et al. | 363/132.
|
4652807 | Mar., 1987 | Nagura | 318/778.
|
4724680 | Feb., 1988 | Kawai | 62/115.
|
4785225 | Nov., 1988 | Horie et al. | 318/811.
|
4959969 | Oct., 1990 | Okamoto et al. | 62/157.
|
5088297 | Feb., 1992 | Maruyama et al. | 62/228.
|
5164651 | Nov., 1992 | Hu et al. | 318/778.
|
5179842 | Jan., 1993 | Kanazawa | 62/158.
|
5422557 | Jun., 1995 | Lee et al. | 318/807.
|
5444344 | Aug., 1995 | Vincent | 318/599.
|
Primary Examiner: Thorpe; Timothy S.
Assistant Examiner: Solak; Timothy P.
Attorney, Agent or Firm: Bushnell, Esq.; Robert E.
Claims
What is claimed is:
1. A method of controlling a reciprocating compressor operated by a
single-phase induction motor, said method comprising the steps of:
(1) starting the reciprocating compressor at a minimum speed in which a
frequency of 45-52 Hz is applied to the single-phase induction motor;
(2) automatically determining by a programmed microprocessor whether the
compressor is operating normally; and
(3) when the compressor is operating normally operating the reciprocating
compressor at a predetermined normal rotational speed.
2. The method of claim 1, wherein, after the first step and before the
second step, the following steps are carried out:
(1a) automatically determining by a programmed microprocessor whether the
compressor is operating normally; and
(1b) when the compressor is operating normally, operating the compressor at
a speed in which a frequency of 52-60 Hz is applied to the motor.
3. A method of decreasing noise and vibration when starting a reciprocating
compressor operated by a single-phase induction motor, said method
comprising the steps of:
(1) starting the compressor by feeding power to the motor at 45-52 Hz;
(2) automatically determining by a programmed microprocessor whether the
compressor has started and is operating normally;
(3) when the compressor has started and is operating normally, feeding
power to the motor at 52-60 Hz;
(4) automatically determining by programmed microprocessor means whether
the compressor is operating normally;
(5) when the compressor is operating normally, feeding power to the motor
at 60 Hz and operating it at a predetermined normal rotational speed.
Description
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and
claims all benefits accruing under 35 U.S.C. .sctn.119 from an application
for METHOD FOR CONTROLLING RECIPROCATING COMPRESSOR HAVING VARIABLE
CAPACITY earlier filed in the Korean Industrial Property Office on Jun 17,
1998 and there duly assigned Serial No.22680/1998.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a compressor for a cooling apparatus, and
more particularly, to a method for controlling a reciprocating compressor
having variable capacity, which is capable of varying a rotational speed
thereof.
2. Description of the Related Art
Generally, a compressor is used for compressing a refrigerant at a high
temperature and a high pressure, which circulates in an apparatus for
generating cool air. There are many kinds of compressors such as a
reciprocating compressor, a rotary compressor, a brushless direct current
(BLDC) compressor and an inverter type compressor.
A single-phase induction motor is typically used in the reciprocating
compressor and the rotary compressor. As shown in FIG. 1, a frequency of
50 or 60 Hz is used to start the compressors. In the above mentioned
compressors which use the single-phase induction motor, only an on/off
operation of the compressors is controlled without any variation of a
rotational speed thereof.
Meanwhile, in an reciprocating compressor having variable capacity, the
rotational speed of the compressor can be controlled by varying a supplied
voltage or frequency. Therefore, a flow rate of the refrigerant is
facilely adjusted by the variation of the rotational speed of the
compressor, whereby the cooling apparatus itself can be directly
controlled. FIG. 3 shows a structure of a control board in connection with
the reciprocating compressor having variable capacity.
In the FIG. 3, a motor 1 of the reciprocating compressor having variable
capacity is driven by an inverter 3 operated by an output signal from a
programmable array logic (PAL) 2. The PAL 2 is controlled by a
microcomputer 10. The rotational speed of the motor 1 is input to the
microcomputer 10 through a back emf sensing part 4. Therefore, the
microcomputer 10 precisely controls the speed of the motor 1 referring to
the input data of the speed of the motor 1.
The microcomputer 10 comprises a mode selecting part 11, a commutator 12
which receives a signal from the mode selecting part 11 and outputs a
commutation signal to the PAL 2, a step signal generating part 13 which
generates a step signal and transmits the step signal to the mode
selecting part 11, a digital-phase shifter 14 which converts the signal of
the rotational speed from the back emf sensing part 4 into a correspondent
digital phase shifter signal and transmits the digital phase shifter
signal to the mode selecting part 11, and a PWM pulse part 15 which
applies a pulse width modulation (PWM) signal to the PAL 2.
However, in the above mentioned reciprocating compressor having variable
capacity, there is a problem that, since an angular velocity of a shaft of
the compressor is much lower than that of the conventional compressor
using the single-phase induction motor, a lubricating oil is not
sufficiently supplied to a sliding portion of the compressor when the
compressor is operated at a minimum speed, whereby a reliability of parts
of the compressor is lowered.
To overcome the above problem, there has been suggested a method which
starts a compressor at a frequency of 58 Hz. However, in the method, there
is a problem.
In addition, in the conventional reciprocating compressor having variable
capacity, there is a problem that a noise and vibration due to a sudden
change of the rotational speed of the compressor is generated when
changing the speed from the maximum to the minimum or reversely.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to secure the
reliability of the parts of the compressor when starting and reduce the
switching loss of the control board.
The other object of the present invention is to minimize the generating of
the noise and vibration due to a sudden change of the rotational speed.
To achieve the above objects and other advantages, there is provided A
method of controlling a reciprocating compressor comprising of:
starting the reciprocating compressor at a minimum speed in which a
frequency of 45-52 Hz is applied; and
operating the reciprocating compressor at a predetermined rotational speed.
Further, according to the present invention, the method according to claim
1, further comprising a step of operating the reciprocating compressor at
a frequency of 52-60 Hz before operating at the predetermined rotational
speed.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention, and many of the attendant
advantages thereof, will be readily apparent as the same becomes better
understood by reference to the following detailed description when
considered in conjunction with the accompanying drawings in which like
reference symbols indicate the same or similar components, wherein:
FIG. 1 is a graph connected with a starting method of a conventional
compressor using a single-phase motor;
FIG. 2 is a graph connected with a operation control method of the
conventional compressor using a single-phase motor;
FIG. 3 is a block diagram of a control board of a reciprocating compressor
having variable capacity;
FIG. 4 is a flow diagram of a operation control method of a reciprocating
compressor having variable capacity according to the present invention;
FIG. 5 is a graph showing a change of the rotational speed when starting at
a minimum rotational speed according to the present invention; and
FIG. 6 is a graph showing a change of the rotational speed when changing
the rotational speed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention now will be described more fully hereinafter with
reference to the accompanying drawings, in which preferred embodiments of
the invention are shown.
In FIGS. 3 and 4, a method of controlling a reciprocating compressor having
variable capacity according to the present invention is as follows:
First of all, it is determined whether the reciprocating compressor is
started at a minimum rotational speed (S10). If the reciprocating
compressor is started at the minimum rotational speed, the reciprocating
compressor is started at a frequency of 45-52 Hz (S20). Then, it is
determined whether the starting of the reciprocating compressor is
completed at the starting frequency (S30). If the starting of the
reciprocating compressor is completed, the reciprocating compressor is
operated at a frequency of 52-60 Hz (S40). Sequentially, it is determined
whether the reciprocating compressor is normally operated at the operating
frequency (S50). If the reciprocating compressor is normally operated at
the operating frequency (S50), the reciprocating compressor is operated at
a predetermined speed (S60).
The starting frequency (45.about.52 Hz) and the operating frequency
(52.about.60 Hz) applied to the present invention are obtained by a
experimentation. That is, as a result of a analysis of data obtained by
the experimentation, if the starting frequency is applied to the
reciprocating compressor when starting, an optimum amount of lubricating
oil is supplied to a sliding part of the reciprocating compressor and the
reliability of parts thereof is secured. In addition, if the operating
frequency is applied to the reciprocating compressor after completion of
the starting, a noise and vibration due to a sudden change of the
rotational speed is minimized when varying the rotational speed from a
minimum speed to a maximum speed or reversely.
The operation of the reciprocating compressor having variable capacity
according to the present invention is described more fully.
First, if a starting rotational speed is determined according to a program
in a microcomputer 10 of the control board, the microcomputer 10 controls
a programmable array logic (PAL) 2 and an inverter 3 through a pulse width
modulation (PWM) pulse part 15 and a commutator 12 and applies a frequency
of 45.about.52 Hz to a motor 1 of the reciprocating compressor so that the
motor 1 is started. At this time, the reciprocating compressor is operated
at a predetermined minimum rotational speed. FIG. 5 show a variation of
the rotational speed of the reciprocating compressor.
In FIG. 5, a rotational speed of the reciprocating compressor is 2880 RPM
corresponding to the starting frequency (45.about.52 Hz) and the minimum
rotational speed is 2200 RPM.
If the starting frequency is applied to the motor 1 and the starting
operation is completed (S30), the microcomputer 10 applies a frequency of
52.about.60 Hz to the motor 1 (S40) so that a noise and vibration due to a
sudden change of the rotational speed is minimized when varying the
rotational speed from a minimum speed to a maximum speed or reversely. If
the reciprocating compressor is normally operated after the starting
operation, the microcomputer 10 operates the reciprocating compressor at
the predetermined speed (S60). FIG. 6 shows a variation of the rotational
speed of the reciprocating compressor.
As shown in FIG. 6, the rotational speed of the reciprocating compressor is
increased from 2200 RPM to the 4100 RPM.
According to the present invention, an optimum amount of lubricating oil is
supplied to a sliding part of the reciprocating compressor so that the
reliability of parts thereof is secured.
This invention has been described above with reference to the
aforementioned embodiments. It is evident, however, that many alternative
modifications and variations will be apparent to those having skill in the
art in light of the foregoing description. Accordingly, the present
invention embraces all such alternative modifications and variations as
fall within the spirit and scope of the appended claims.
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